Selective blinkfulness

Normally, I leave Firefox set to only show GIF animations once (image.animation_mode = once in about:config) — it’s just too hard to concentrate with all that motion going on all over the page. But there is one time when the perpetual animation would serve a useful purpose for me: when I’m monitoring a build on the Hudson CI server, the currently executing job is highlighted with a blinking ball:

My once setting foils the blinkiness of the ball. It’s too much effort to go to about:config and change the setting just to monitor the build — I was wishing for a toolbar button that would toggle the setting for me.